Teradata DBMS has consistently supported compression in various forms.
Multi-Value Compression (MVC) was introduced in version 5.0, Algorithmic (ALC) and Block Level (BLC) compression in version 13.10, and version 14.0 introduced various automatic compression options for Columnar tables.
Implementing Teradata compression with MVC or ALC can lead to savings in disk space and improved performance. However, it requires a significant investment in manpower, which can be expensive.
It is important to remember that data demographics change over time, necessitating regular revisiting of compression analysis, which may occur annually.
Are the benefits of dedicating time to compression worth the costs? While certain tools may assist with compression, the purpose of this article is to raise this question. As with most matters, it boils down to a “cost versus benefit” analysis.[su_shadow][su_panel]On one recent customer engagement, I produced the following analysis for them:
- They have about 98000 tables.
- About 26000 tables have MVC implemented.
- On their system, only 4000 tables are big enough that a full table scan is estimated to take longer than 1 second – even allowing for a reduced scan rate because of concurrent queries.[/su_panel][/su_shadow]
It is unnecessary to remove the current MVC compression for small tables. MVC compression does not have any CPU overhead, and the negligible benefits of eliminating compression on multiple tables are not worth the effort. However, some savings may be achievable if ALC is used on a small table.
When designing or modifying tables, carefully considering the compression setting is advisable.
If the table is small, compression may not be needed. This is a matter of process alteration rather than remediation.